The invention relates to an electro-hydraulic actuator and to a fast-switching magnetic valve for use therein, and has use particularly with control surfaces in aircraft.
By means of an electro-hydraulic actuator, it is possible to control movable surfaces of relatively high power level in aircraft, for example aircraft rudders, by electrical signals. In order to achieve the degree of safety necessary in aircraft, high demands are made for reliability in the actuator, in particular for the reliable recognition of breakdowns.
In the prior known actuators in aircraft, designed as servo circuits, the critical elements in relation to the reliability are the means for the provision of feed back and the servo valve. Owing to the analogue processing of signals, the recognition of breakdown presents difficulties. Also, with known actuators which operate with pilot valves in place of servo valves, the provision of feed back has been retained in such devices proposed up to the present time.
A basic object of the invention is to devise an actuator which is very simple in its construction and in its function and by means of which it is possible to recognize breakdowns with certainty without additional systems being necessary for this purpose.
A further object is to devise a magnetic valve which can be used particularly advantageously in the construction of the actuator as embodied in the present invention.